1. Field of the Invention
The present invention relates to a rotary encoder able to produce two output signals. More particularly, the present invention relates to a single rotary encoder that can be used as both a shuttle switch and a mode switch.
2. Description of the Related Art
FIGS. 1 and 2 illustrate two rotary encoders according to the prior art. In FIG. 1, a light receiving plate 24 and a light encoding plate 23 are engaged to the cylinder of a fixing base 27 so as to be rotatable about a shaft 11, and an output signal is produced by the rotation of fixing base 27. Similarly, in FIG. 2 a light emitting diode 20 is supported by support 30 so as to transmit light through holes in plate 1 to be received by a light receiver beneath the plate 1 (not shown), by which means a pulse signal is generated by alternating the receiving and not receiving of light by the light receiver. These types of rotary encoder can be applied as a shuttle switch to control a parameter of an electronic device, for example the brightness of a computer monitor.
However, in practical application, an electronic device usually has a plurality of parameters that the user needs to control. For example, a computer monitor might have the parameters brightness, sharpness, and color. To allow control of these three parameters, the monitor would require three shuttle switches. As an alternative, a monitor could include a mode switch for each of the parameters and a single shuttle switch. If the user desired to adjust the contrast, he could press the mode switch corresponding to contrast and then use the shuttle switch for adjusting the value.
In both of these examples, a plurality of switches are required to control a plurality of parameters. This increases the cost of the device.